A brake device for a hoist frame drivable by means of a linear motor has become known from patent specification DE 41 06 595, wherein load cells produce a releasing signal. Brakes arranged at the hoist frame embrace the guide rails arranged in the conveying shaft, wherein a brake is provided for each guide rail. The brake has a brake shoe for each limb side of the guide rail. Actuating elements produce, for each brake shoe, braking forces on the guide rail by means of the brake shoe, wherein the action of a spring activates the brake and a hydraulic cylinder opposes the spring force and releases the brake.
A disadvantage of such known equipment resides in the fact that the brake produces different braking moments in the case of normal operation and in the case of failure of a brake half. In the known brake one brake half generates the necessary braking moment; the two brake halves together produce twice the braking moment, which in the case of normal operation can lead to slipping of the cable on the drive pulley. The strands in the case of a steel cable are, and the casing in the case of a synthetic fibre cable is, thereby very highly loaded or excessively worn.
A lift drive with a disc brake, the brake calliper of which is mounted to be floating, has become known from specification JP 04133988. The brake is actuated by means of a compression spring and released by means of an actuator acting against the compression spring. When the brake is released the brake calliper is moved by means of another compression spring into the initial position.
A disadvantage of that type of equipment resides in the fact that in the event of spring breakage or wearing away of a brake lining the brake fails.